You probably got votes from people with low steempower.

Have a read of the following FAQ to see how steemit works:

https://steemit.com/steemit/@thecryptofiend/the-missing-faq-a-beginners-guide-to-using-steemit

You can also see how powerful the votes you get are by looking at your article in steemd.com. Just put steemd in the url instead of steemit. Here is the steemd analysis for this post:

https://steemd.com/howto/@jimcropper/how-do-i-get-20-upvotes-on-a-post-yet-get-no-steem-dollars-no-credit-at-all-for-anything

Click the above link and then click "advanced mode" on the top right. Then scroll down and click "vote details". It should give you a breakdown of who has voted and how powerful they are (the more powerful the more rshares they distribute).